so lately my car has literally been getting about 160 miles per tank or so. The car is lightly modded (intake, exh, mbc), but even for a while with that stuff on it was normal.

-Im literally driving slow as possible to make it last..
-i went and had the AFR checked (it was fine)

My clutch is slipping a lot...would that reduce the MPG that much though?

Plllllz helP!

 

Slipping clutch could definitely be a factor. Check your vacuum lines too

 

what milage were you getting before?

 

Ok well I guess that's a good thing haha. I was getting at least 200!

 

Slipping could be a factor but I'd hope you'd still get better than 150 to a tank. Check all your hoses and clamps under the hood to ensure they are tight. Something certainly isn't right.

 

I've seen instances where clogged/bad O2 sensors on various cars cause terrible gas mileage. Do you have a wideband installed? Is that how you had AFR checked or did a shop do it and hook up to stock O2 sensors?

 

Check your BOV and make sure that's not leaking as well. I had one that leaked and was causing me to only get about 15-16mpg.

 

Don't feel bad I got a stock evo 2011 and I get same mpg as you

 

z chip

 

That's a problem, dude. I've got a stock '11 GSR, and I'm getting better mileage than I was in my Ralliart (about 23 mpg combined driving).

 

Lead foot causes bad gas mileage

 

whats even wierder is that on my MR i changed it to sport mode for pretty much all driving except freeway. i've been going from 180miles on a tank to about 230. it makes no sense to me, and sport is more fun to drive anyways. "on a tank" refers to the exact moment my gas light dings, not til empty.

 

Is there a shop up by you somewhere? I would check all hoses are spots you could have a leak, Do you have a test pipe? Maybe the cat is clogged? And I would take it to get tuned and ditch the zchip..

 

Did this guy ever find out what his problem was?

Im having the exact same problem. I went to getting 300-360 per tank to 150 or so.

Dang....

And until now this has been a flawless car with over 50,000 miles on it and driven all over the country, literaly-

 

I'd highly recommend changing out the spark plugs. I had one destroy itself in under 50,000km took it exactly 46,000, two track days and 400 1:4 passes tho n a bad tune.

As stated check your a/f even tuned it could be running crazy rich. I was running 10s and was getting about what you guys are. I switched plugs retuned and now get easily 500km per tank making 340/360. If no cats, try plugs n af